Stirling engines have been known as an environment-friendly heat engine having a high heat efficiency in theory. Typically the stirling engine has a power piston called “displacer” that reciprocates in a cylinder. Improvements have been made on the stirling engine in recent years including, for example, a diaphragm mechanism.
The stirling engines having a reciprocating displacer need provision for a mechanism for converting the reciprocating movement to the rotational movement of a drive shaft and a fly wheel in order to maintain rotation at a constant speed assisted by inertia. The stirling engines of this type are thus disadvantageous in mechanical efficiencies.
An improved stirling engine is disclosed in JP 2003-83160A having a disc-shaped displacer capable of converting volume changes to rotating movement not to reciprocating movement.
The rotary stirling engines of the above type are advantageous because they are free of power pistons, fly wheels or other components which may adversely affect the mechanical efficiency of the engine. However, they require a large temperature differential to obtain high heat efficiencies since they use a gas as a working fluid.